反倾岩质边坡的时效变形破坏研究

Time Dependent Deformation of Antithetic Dip Rock Slope

为研究反倾岩质边坡的变形破坏规律性与形成机制,以黄河上游茨哈峡水电站库区反倾岩质边坡变形破坏为例,基于系统的工程地质方法并结合离散元模拟边坡的变形演化进程,对其倾倒变形的时效性进行了分析并研究了其形成演化机制。结果表明:1该倾倒边坡的时效变形规律表现为倾倒变形在不同方向上具有差异性,其时空演化特征表现为斜坡顶部的拉裂和中部的弯曲变形,目前倾倒体内未形成贯通性失稳界面,倾倒拉裂和弯曲变形同时存在,表现为倾倒机制的长期性、积累性和阶段性;2该类斜坡的变形破坏是岩层在自重应力作用下做悬臂梁弯曲,岩层发生弯曲变形,导致坡体后缘开裂、根部折断、前缘剪切蠕变,当坡体折断带内的剪应力超过其抗剪强度时,坡体逐渐错动下滑形成倾倒塌滑体;3该倾倒变形体的破坏模式为弯曲—拉裂变形、弯曲—折断破裂、蠕滑—拉裂变形、表层滑塌和深部滑坡形成。

In order to study the deformation failure regularity and formation mechanism of antithetic dip rock slope, a case study of slope at Cihaxia Hydropower Station Reservoir in the upstream of Yellow River, northwest of China was presented. Based on the engineering geological approach combined with discrete element simulation of the slope evolution process, we analyzed its toppling time dependent deformation and evolution mechanism. The results showed that： （1） The time dependent deformation regularity of the toppling was characterized as dissimilarity in different directions. The specific space-time evolution of the slope showed that the upper part of the slope tension- cracking and the middle,part of the slope flexural deformation. At present, the toppling has not formed connected unstable interface, meanwhile toppling-tension-cracking and flexural deformation exist, therefore, it shows long- term, progressivity and periodicity of the toppling mechanism. （2） This kind deformation failure should be cantile- ver beam bending by gravity and the stratum flexural deformation result in the rear edge of the slope cracking, root breaking and front shearing-creeping. When the shear stress exceeds the shear strength inside the slope, the slope gradually slides and forms collapse or landslide. （3） The toppling deformation failure mode should be bending-ten- sion-cracking deformation, bending-breaking rupture, creep-tension-cracking deformation, shallow collapse and deep landslide.